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Remove Power Amp From A100?

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  • Remove Power Amp From A100?

    I want to run my A100 from a 1/4" line out taken off the GG terminals on the preamp in to an external amp and then to my leslie which has a 1/4" jack to the crossover then to the speakers. I do not want the internal speakers to be active. I have disconnected the speakers at the speaker output terminals on the power amp. I'm told this is not good for the power amp. Can I remove the power amp completely? If so, how do I get AC power to the organ? since the AC plug is on the power amp? Any advice would be appreciated.

  • #2
    Re: Remove Power Amp From A100?



    Hey Rod,</P>


    Unless you want the original amp and speakers out of there for a chop (i.e. to try to make it look more like a B3), the simplest solution is just to pull the tubes out of the power amp &amp; reverb amp. This way the AO-39 continues to supply power to the AO-28 - and the rest of the organ! The real downside is that you lose the reverb signal when you do this, because it's actually the speaker-level signal out of the AO-39 that drives the reverb tank itself.</P>


    With that said: you were told right, you DON'T want to continue running the power amp withno speaker load! I believe the main internal speakers are two 12-inch, 8 ohm models wired in parallel for an effective load of 4 ohms. Then the reverb amp (AO-35 or AO-44) has its own 12-inch, 8 ohm speaker. So you need a big fat resistor across the output of both of those if you keep everything running with no speakers: something like 8 ohm, 20W for the reverb ampand 4 ohm, 20W for the main amp.</P>


    hope this helps-</P>


    td</P>
    Nobody loves me but my mother,
    And she could be jivin' too...

    --BB King

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    • #3
      Re: Remove Power Amp From A100?

      Both amps require 8 ohm load resistors. There is a pair of 16s on the mains. 15-20 watts should do it or two 10s in parallel.

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      • #4
        Re: Remove Power Amp From A100?

        Sorry to be contrary H101, but the schematic shows 2 x 8 ohms in parallelon the AO-39. I seem to remember this being borne out once when I put a meter on them.
        Nobody loves me but my mother,
        And she could be jivin' too...

        --BB King

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        • #5
          Re: Remove Power Amp From A100?



          Just pull the amp tubes. Done.</p>

          Geoelectro
          </p>

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          • #6
            Re: Remove Power Amp From A100?

            So, just pulling the tubes looks like an easy route. There are no downsides to doing that?

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            • #7
              Re: Remove Power Amp From A100?



              Nope, as long as you pull the 5U4, no high voltage is being sent through it.</p>

              Geoelectro
              </p>

              Comment


              • #8
                Re: Remove Power Amp From A100?



                [quote user="toasterDude"]Sorry to be contrary H101[/quote]</P>


                Best take me out back and flogg me! I must have had Leslie amps on the brain.</P>

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                • #9
                  Re: Remove Power Amp From A100?



                  [quote user="rodreb"]So, just pulling the tubes looks like an easy route. There are no downsides to doing that?[/quote]</p>

                  </p>

                  It's fine, I've been running mine like that for a couple of years now. Just carefully box up all the tubes, someday you might want them back in.
                  </p>
                  - Don
                  '60 A100 - '62 Leslie 45
                  '47 CV - MS Pro3T
                  Nord Electro 2 73
                  MAudio Prokeys 88SX

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                  • #10
                    Re: Remove Power Amp From A100?

                    I'm not quite sure what happened but, my replies thanking everyone for their answers did not post so, I'll try again.

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